Campylobacter jejuni is a Gram-negative spiral microaerophilic bacterium that has been recognized as a cause of secretory type diarrhea and enteritis (Ref. 1). Throughout this application, various references are referred to in parenthesis to more fully describe the state of the art to which this invention pertains. Full bibliographic information for each citation is found at the disclosed end of the specification immediately preceding the claims. These references are hereby incorporated by reference into the present disclosure). The flagellum of C. jejuni is responsible for bacterial motility which enhances the organism's pathogenicity. The flagellum consists of three major components; the filament, the hook, and the basal body (Ref. 2). A campylobacter cell carries a single unsheathed flagellum at one or both poles of the body. The flagella are responsible for the high motility of the organisms as aflagellate mutants are nonmotile (Refs. 3, 4, 5, 6, 7, 8, 9). A number of studies indicated that the polar flagellum plays an important role in colonization of the viscous mucus lining of the gastric intestinal tract and that it is an important virulence determinant (Refs. 3,4,7,10,11).
The basic structure of the bacterial flagellum consists of a propeller (filament) connected via a universal joint (hook) to a transmission shaft, motor and brushings (basal body) embedded in the cell envelope (Ref. 12). The flagellar filament consists of several thousand self-assembling protein (flagellin) monomers arranged in a helix. These form a hollow tube of relatively constant diameter and variable length with an over corkscrew morphology.
Most eubacterial flagellar filaments that have been characterized appear to be composed of a single kind of flagellin (Ref. 8). However a number of Eubacteria have now been shown to possess multiple flagellingenes (Refs. 6, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22), C jejuni (Refs. 13, 15, 17, 21) and C. coli (Refs. 6, 13) have been reported to have two flagellin genes (flaA and flaB). In C. jejuni, the flagellin genes flaA and flaB have been isolated and sequenced, however prior to the present invention a third flagellin gene had not been isolated and characterized.
It would be advantageous to provide nucleic acid molecules encoding flagellin proteins of the flagella for strains of Campylobacter and purified flagellin proteins, including flaC for use as antigens, immunogenic compositions, including vaccines, carriers for other antigens and immunogens and the generation of diagnostic reagents.